Electron device manufacturing method, a pattern forming method, and a photomask used for those methods

ABSTRACT

A method of manufacturing an electron device provided with minute structure such as a semiconductor integrated circuit using projection exposure technique and phase shift mask technique, maintaining a high yield is disclosed. In an electron device manufacturing method according to the invention, a desired electron device is manufactured by printing a light shielding film pattern on a photosensitive film provided on the surface of a workpiece by a projection tool using a mask where a phase shifter having predetermined thickness is partially formed on the flat surface of a transparent plate and a light shielding film having a predetermined pattern and made of nonmetal is partially provided with the film covering the end of the shifter and developing the photosensitive film. Further, concretely, the above pattern is printed using a mask where the light shielding film made of non-metal is partially extended on the surface of the shifter and the transparent plate including the end of the shifter by the projection tool. According to the electron device manufacturing method according to the invention, an electron device provided with minute structure can be precisely manufactured maintaining a high yield.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method of manufacturing anelectron device such as a semiconductor device, a superconductivedevice, a micro machine and an electronic device, a pattern formingmethod used for the method, a photomask used for these methods and itsmanufacturing method, particularly relates to technique effective toapply to exposure technology in a process for manufacturing asemiconductor integrated circuit.

[0003] 2. Description of the Related Prior Arts

[0004] In manufacturing a semiconductor integrated circuit, for a methodof printing a minute pattern on a semiconductor wafer, lithography isused. In lithography, a projection tool is mainly used, a pattern of aphotomask installed in a projection tool is printed on a semiconductorwafer and a device pattern is formed.

[0005] A normal photomask is produced by processing light shieldingmaterials such as chromium (Cr) formed on the flat surface of atransparent quartz substrate. That is, a light shielding film made ofchromium or others is formed on the flat surface of a quartz substratein a desired shape. For the processing of the light shielding film, forexample, after an electron beam sensitive resist is applied on the lightshielding film, a desired pattern is written on the electron beamsensitive resist by an electron beam writer, next, a resist pattern in adesired shape is formed by development, afterward, dry etching or wetetching is applied using the resist pattern as a mask and the lightshielding film is processed. Afterward, after the resist is removed,cleaning and others are performed and a light shielding pattern in adesired shape is formed on the transparent quartz substrate.

[0006] Recently, the integration of LSI has been accelerated, theenhancement of the operational speed has been demanded and theminiaturization of a circuit pattern has been demanded. This tendencyparticularly remarkably appears in a gate pattern that has a largeeffect upon the operational speed of a transistor. For a part of logicLSI products, a gate pattern of 0.1 μm is also already formed using aKrF excimer laser (wavelength: 248 nm) for exposure.

[0007] For a semiconductor memory, miniaturization is accelerated toreduce the cost and a dynamic random access memory (DRAM) according to arule that half pitch is 0.18 μm is manufactured using a KrF excimerlaser for exposure. DRAM according to a rule that half pitch is 0.13 μmusing a KrF scanner is also developed.

[0008] It is owing to an exposure method called super resolution that byfar smaller patterning than the wavelength of exposure is enabled. Superresolution effective to form a minute pattern is called phase shiftlithography and is disclosed in Japanese published unexamined patentapplication No. Sho 58-173744 for example. The phase shift lithographyis a method of forming structure called a phase shifter for alternatelyinverting the phase of exposure light in windows in which a part whereexposure light is transmitted of a photomask, that is, a glass face isseen with a light shielding part between the windows and exposing usingthis photomask. As the phase of light transmitted in both transmittedparts is inverse, the amplitude of light may be zero in the lightshielding part between the parts. In case the amplitude is zero, theintensity of light is also zero and the resolution is greatly enhanced.

[0009] For an example of the disclosure of another technique related toa mask, Japanese published unexamined patent applications No. Hei9-211837 and No. Hei 5-289307 can be given.

[0010] For a phase shifter, there are a carved type that a part of aglass plate as a photomask is carved, a type that a transparent filmhaving the thickness enough to invert the phase is formed on the basematerial of a photomask and a type that these two are mixed.

[0011] A carved type phase shift mask is produced as follows. As shownin (a) of FIG. 2A, a Cr film 202 made of light shielding material isdeposited on the flat surface of mask base material (a quartz substrate)201 by sputtering and an EB resist 203 is applied to it. A pattern forlight shielding is written by EB (shown by an arrow 204). The pattern isdeveloped, a resist pattern 205 is formed ((b) of FIG. 2A), the Cr film202 is etched by dry etching or wet etching ((c) of FIG. 2A), the resistis removed and a light shielding pattern 206 is formed C(d) of FIG. 2A).Afterward, an EB resist 207 is applied and a pattern for forming a phaseshifter is exposed (shown by an arrow 208)((e) of FIG. 2A). Developmentis performed, a resist pattern 209 is formed ((f) in FIG. 2B) and thequartz substrate is carved by desired depth by dry etching ((g) of FIG.2B). The resist is peeled, phase difference between both apertures 210and 211 is inspected ((h) of FIG. 2B), in case carved quantity formaking phase difference does not reach a target value, an EB resist 212is applied again, a shifter pattern is written 213 ((i) in FIG. 2B),development is performed, a shifter pattern 214 is formed ((j) in FIG.2B), the quartz substrate is etched again by dry-etching ((k) in FIG.2C), the resist is peeled and phase difference is inspected ((l) in FIG.2C). Afterward, as shown in (m) of FIG. 2C, wet etching is performed,overhang structure 215 having the Cr film as an overhang is formed and acarved type phase shift mask is manufactured.

[0012] In the meantime, a transparent film formation type (hereinaftercalled an additive phase shifter type) phase shift mask is produced asfollows. As shown in (a) of FIG. 3A, a Cr film 302 made of lightshielding material is deposited on the flat surface of a mask substrate(a quartz substrate) 301 by sputtering and an EB resist 303 is appliedon it. A pattern for light shielding is written by EB (304). Developmentis performed, a resist pattern 305 is formed ((b) of FIG. 3A), the Crfilm is etched by dry etching or wet etching ((c) of FIG. 3A), theresist is removed and a light shielding pattern 306 is formed ((d) ofFIG. 3A).

[0013] Afterward, a spin-on-glass (SOG) film is applied, heatingprocessing and others are performed and a transparent shifter 307 isformed ((e) in FIG. 3A). Afterward, an EB resist 308 is applied and apattern for forming a phase shifter is exposed (309) ((f) in FIG. 3B).Development is performed, a resist pattern 310 is formed ((g) in FIG.3B) and a transparent shifter is etched by dry etching or wet etching((h) in FIG. 3B). The resist is peeled, phase difference between bothapertures 311 and 312 is inspected and a phase shift mask is acquired((i) in FIG. 3B).

[0014] For light shielding material in both methods, the metallic Crfilm is used and in addition, as the accuracy of the light shieldingpattern is required, the metallic Cr film is formed on the flat surfaceof the quartz substrate by sputtering.

[0015] For the type of the phase shift mask, there are a shifter edgetype that phase difference is given to the light shielding pattern 401which can be regarded as an optically isolated pattern as shown in FIG.4 by optical path difference 402 on both sides of the light shieldingmaterial 401 and Levenson type that a phase shifter 502 is alternatelyarranged on a light shielding pattern 501 closely assembled like a lineand space as shown in FIG. 5 in an aperture. Reference numbers 403 and503 in FIGS. 4 and 5 both denote a glass substrate. In both cases,structure for inverting the phase of exposure light transmitted in theaperture on both sides of the aperture is also provided.

[0016] A problem in the printing characteristics of the carved typephase shift mask is that the quantity of transmitted light in anaperture 602 (hereinafter called a phase 0) in which a glass substrate601 is not carved or is not carved so much as shown in (a) of FIG. 6 andin an aperture 603 (hereinafter called a phase π) in which the glasssubstrate is deep carved varies by light scattering on the side 605 ofthe glass substrate formed under the side wall 604 of Cr light shieldingmaterial and the dimension difference of a pattern called 0/π differenceis caused by the variation.

[0017] To prevent this, a side etch carved type that the glass side 611is backed from the edge 612 of Cr light shielding material 613 as shownin (b) of FIG. 6 and light scattered on the glass side is shielded bythe Cr light shielding material is proposed.

[0018] However, in this case, there is a problem that the width 614 ofglass supporting the Cr light shielding material 613 is thinned as thepattern is miniaturized and miniaturization is impossible in view of thestrength. Particularly, in a both sides carved type of mask in which theglass substrate 601 is also carved in the phase 0 602 as shown in (c) ofFIG. 6, the problem of area in which the Cr film and the glass aretouched is a large problem. The Cr light shielding material 613 isrequired to be supported by a thin glass support 616 and as a patternbecomes complex and minute, the problem becomes more serious.

[0019] Further, recently, the magnification of a mask of a lithographyequipment progresses from “10×” to “5×” and further, to “4×”, hereby, asa dimension on the mask is required to be further acceleratedly reducedby the reduction of a device dimension, the thinness of the support is adefinite problem that determines the limit of printing. In manufacture,there is a problem that foreign matters accumulate in a pocket 615 andthe yield of masks is hardly enhanced. When the shifter is carved by dryetching, there is a problem that carved depth differs depending upon apattern dimension by micro loading effect in etching and therefore, aphase angle differs according to the pattern dimension. Further, Asshown in FIGS. 2A to 2C, there is a problem that as the number of maskmanufacturing processes is many, a mask manufacturing cost is high, timerequired for manufacture is long, turn around time (TAT) is large andthe number of processes is many, the yield is low.

[0020] In the meantime, in the additive phase shifter type phase shiftmask,.as shown in FIG. 5, there is a problem that as the shifter 502 isformed on the Cr light shielding film 501 made of light shieldingmaterial, the phase shifter cannot be formed with fixed thickness, thephase angle varies according to a pattern dimension and the phase (thatis, the thickness of the shifter) varies between the center 504 of thepattern and the periphery 505 in one pattern.

[0021] Furthermore, even if a phase shifter is produced beforehand andthe formation on the phase shifter of a Cr light shielding film is triedto solve the problems, it is extremely difficult to form a Cr film freeof a defect and having high quality by sputtering on a substrate havingdifference in a level because of the shifter. Further, there is aproblem that as the Cr film made of light shielding material is formedon the shifter, the surface of the Cr film is not flat, the Cr film hasinclined or irregular structure, exposure light is largely reflected anda pattern printing characteristic is deteriorated. For example, as shownin FIG. 16, it is proposed that a countermeasure for forming a Cr oxidelayer 1404 for preventing reflection on the surface of a Cr film 1403formed on blanks 1401 made of a quartz transparent substrate andpreventing reflection from the surface of the Cr film using a thin filminterference phenomenon is taken, however, there is an extremelyimportant problem in accelerating a minute pattern that as a part of theCr film covers a shifter pattern 1402, the Cr film has an inclined orirregular surface, a diagonal part 1405 is partially formed, as thethickness of the Cr oxide film there cannot be precisely controlledaccording to a predetermined reflection prevention condition, thereflectivity partially differs as shown by arrows 1406 and 1407 in FIG.16 and a printing characteristic is deteriorated.

[0022] Therefore, it has been more and more difficult to manufacture theelectron device provided with the complex and minute patterns using sucha mask and a projection tool precisely and with a high yield.

SUMMARY OF THE INVENTION

[0023] Therefore, the object of the invention is to provide the improvedmanufacturing method of an electron device using a phase shift mask. Forexample, the object is to provide a method of manufacturing an electrondevice formed by plural minute patterns having the width and an intervalof 0.1 μm or less using a projection tool and phase shift mask techniquewith a satisfactory yield.

[0024] Another object of the invention is to provide a minute patternforming method suitable for the manufacturing method of such an electrondevice and a mask improved for the method.

[0025] Further another object of the invention is to provide improvedtechnique that can enhance the critical dimension accuracy oflithography equipment in a method of manufacturing an electron deviceusing a phase shift mask.

[0026] Further concretely, the object is to provide a minute patternforming method wherein no dimension accuracy is deteriorated by theeffect of reflected light from the surface of light shielding materialin projection exposure using a phase shift mask having high phase anglecontrollability and others and provide a minute electron device usingthe method.

[0027] The outline of the representatives of the inventions disclosed inthis application will be briefly described below.

[0028] That is, in the invention, a phase shifter having predeterminedthickness is partially formed on the flat surface of a transparentplate, a light shielding pattern is printed on a photosensitive filmprovided on the surface of a workpiece using a mask where a lightshielding film that covers the end of the shifter, is made of non-metaland has a predetermined pattern is partially provided by a projectiontool and an electron device is manufactured by developing thephotosensitive film. Further concretely, the pattern is printed byprojection exposure using a mask where the light shielding film made ofnon-metal is partially extended on the surface of the shifter and thetransparent plate including the end of the shifter.

[0029] In another invention, a concavity or a convexity havingpredetermined depth or height is partially formed on the flat surface ofa transparent plate, a light shielding pattern is printed on aphotosensitive film provided on the surface of a workpiece using a maskwherein a light shielding film that covers the end of the concavity orthe convexity, is made of non-metal and has a predetermined pattern ispartially provided by a projection tool and an electron device ismanufactured by developing the photosensitive film. Further concretely,the pattern is printed by projection exposure using a mask where thelight shielding film made of non-metal is partially extended on thesurface including the end of the concavity or the convexity of thetransparent plate and adjacent to the end of the concavity or theconvexity of the transparent plate by projection exposure.

[0030] In any invention, as phase shift means is formed on the flatsurface of the transparent plate, the phase shift angle of exposurelight in the phase shifter in printing can be secured in a predeterminedregion precisely.

[0031] In any invention, for a light shielding film made of non-metal, alight shielding film the reflectivity of exposure light in printing ofwhich is smaller than that on a metallic film such as a Cr film isdesirable and it is desirable that for example, a film made ofdielectric material, high resistance material or organic material isused. Further concretely, it is also favorable to manufacture the maskitself that the light shielding film itself is a photosensitive film andit is desirable that a photoresist made of novolac resin or phenol resinis used. Or it is desirable that a photosensitive film such as apolyaniline resin film is used.

[0032] As the reflectivity of exposure light in printing can be madesmaller than that on a metallic film such as a Cr film from relationwith the refractive index by using a film made of dielectric material,high resistance material and organic material for a light shieldingfilm, a flare can be reduced even if the light shielding film has theirregular surface and the invention is advantageous to enhance theresolution and the dimension accuracy. As described later, as waveguideeffect caused on the side wall due to the thickness of the lightshielding film (that is, a mask pattern) itself can be reduced byexposure light in printing, difference in a dimension after processingmade by the difference in the thickness of the light shielding film canbe reduced even if the light shielding film has the irregular surfaceand the invention is extremely advantageous to enhance processingaccuracy.

[0033] As described above, according to the invention, as a phase shiftangle in a mask can be precisely controlled, and the resolution and thedimension accuracy in printing can be enhanced, the manufacturing yieldof an electron device such as a semiconductor integrated circuitprovided with a complex and minute pattern can be enhanced.

[0034] (a) in FIG. 1 shows an example of a mask according to theinvention. As clear from FIG. 1, the mask has an undernearth phaseshifter additive light shielding mask structure in which a lightshielding pattern 3 made of dielectric material, high resistancematerial or organic material is formed at the end of the phase shifter 2so that the light shielding pattern covers a part having difference in alevel formed by the surface of the phase shifter and the surface of theblanks 1 after a transparent phase shifter 2 patterned on the flatsurface of blanks 1 such as a transparent quartz plate is formedbeforehand. When a mask manufacturing process is considered, a case thatthe light shielding pattern is written on the upside as shown in FIG. 1is easily understood, however, when a mask is inserted into lithographyequipment in printing, the mask is installed in the lithographyequipment in a direction shown in (b) FIG. 1, that is, in a state inwhich the pattern face of the mask is opposite to the surface of aworkpiece 11 to be an electron device of a semiconductor substrate andothers on the surface of which a photosensitive photoresist film 12 isprovided, projected exposure light 15 is radiated from the top, that is,from the rear surface of transparent blanks and the photosensitive film12 on the surface of the workpiece 11 is exposed according to a maskpattern formed by the light shielding material 3. The light shieldingpattern is printed on the photosensitive film by developing the exposedphotosensitive film 12.

[0035] Further, if a transparent film (not shown in FIG. 1) therefractive index n′ of exposure light having the wavelength of λ inprinting of which is larger than the refractive index of the blanksglass and is smaller than the refractive index n of the phase shifter isprovided between the phase shifter 2 and the mask substrate (so-calledblanks glass) 1 so that the following expression is met (the thicknessof the transparent film: d′), dimension accuracy is further enhanced.

sin(2πn′(d′+λ/2(n−1))/λ)=sin(2πn′d′/λ)

[0036] Also, when the section in the direction of the thickness of theend of the phase shifter 2 is an inclined shape (that is, a taperedshape), the dimension accuracy of the light shielding pattern formed onthe phase shifter is enhanced and bonding strength is enhanced, however,as occupied area is increased by the quantity, it is desirable that thetaped angle is 45 degrees or more. Actually, approximately 60 degrees isdesirable.

[0037] Furthermore, if the phase shifter 2 is formed usingphotosensitive SOG, the mask manufacturing process can be greatlyreduced, TAT is also enhanced and further, the yield of the mask is alsoenhanced.

[0038] Further, in case the light shielding pattern 3 in the phase shiftmask was formed by a photoresist film, these inventors found that therewere the following various problems when a photomask was actually usedin the manufacturing process of a semiconductor integrated circuit andin the actual manufacture of the phase shift mask and found theirsolving means.

[0039] First, the detection of a pattern depending upon a so-calledalignment mask between the shifter and the light shielding material anda pattern measurement mark for relatively positioning a shifter patternof the phase shift mask and the light shielding pattern is difficult.This comes into question particularly in case the phase shifter isformed beforehand. The shifter has a type in which the glass substrateis carved and a type in which SOG and others are deposited, and thematerial is the same or the similar as/to the material of the glasssubstrate. Therefore, difference between an electron beam for writingused in alignment and the reflectivity at the edge of the mark of theshifter is small and the detection of a pattern is difficult. Therefore,in case a shifter pattern is formed beforehand, it is difficult to alignthe shifter pattern and the light shielding pattern. Its solving meansis as follows.

[0040] Before the shifter is formed, a metal region made of metal isarranged outside a pattern region to be printed on the surface of themask substrate, that is, outside an integrated circuit pattern formationregion in the manufacture of a semiconductor integrated circuit and analignment mark to be an alignment criterion when a shift pattern and alight shielding pattern are written is formed on the metal. A firstproblem is solved by this means.

[0041] Second, it is difficult to detect a predetermined pattern usedfor detecting various information such as a device discrimination mark.For example, in a mask inspection machine, a tungsten halogen lamp andothers are mainly used for the alignment of a mask, however, astransmissivity in a resist is high and a high contrast cannot beacquired when a detection mark on a mask is formed by a resist patternin case the mask is installed in a mask inspection machine, it isdifficult to detect a pattern. Therefore, it is difficult to align themask and the inspection machine and there is a problem that satisfactoryinspection is impossible. Not only when a mask is installed in theinspection machine but when a mask is installed in lithographyequipment, a mark for identifying the form of a mask is required. Atthis time, it is desirable to enhance work efficiency that a mark whichan operator can read is also provided in addition to a mark read by amachine. At this time, a character directly written on the glasssubstrate with the shifter and resist light shielding material is verydifficult to read and an error in reading occurs. Its solving means isas follows.

[0042] A metal region made of metal is arranged on the mask substrateoutside a pattern region to be printed, that is, outside an integratedcircuit pattern formation region in a method of manufacturing asemiconductor integrated circuit, a criterion mark for aligning with aninspection machine and a mark pattern such as a character and a symbolfor identifying a mask are formed on the metal. At this time, anaperture is formed on the metal, can be also used for a criterion markand an identification symbol, a metal plate is formed, a pattern isformed with the shifter and a resist on the metal plate and can be alsoused for a criterion mark and an identification pattern. A secondproblem is solved by this means.

[0043] Third, a problem that a foreign matter is caused when a mask isinstalled in an inspection machine, lithography equipment and othersoccurs. In the technique described above, as a resist of a mask isdirectly touched to a mask fixing member (for example, a vacuum chuck)of an inspection machine, lithography equipment and others when the maskis installed the inspection machine, the lithography equipment andothers and is carried, a foreign matter is caused because the resistchips or is chipped. There is a problem that as this foreign matteradheres to the surface of a lens of the inspection machine and thelithography equipment, contaminates a chamber and adheres to the surfaceof a semiconductor wafer for example, the inspection accuracy and thedimension accuracy of a pattern are deteriorated and as failure such asthe short circuit of a pattern and the failure of an open circuit occur,the reliability and the manufacturing yield of a semiconductor deviceare deteriorated.

[0044] To solve this problem, these inventors proposed that when aphotomask was installed in predetermined equipment such as theinspection machine and the lithography equipment and was carried, aphotomask in which a light shielding pattern was arranged on theprincipal surface in the center of a mask substrate was used so that thelight shielding pattern made of a resist on the mask substrate of thephotomask and an installing part of the predetermined equipment are nottouched. These inventors also proposed that when a photomask wasinstalled in predetermined equipment, predetermined processing wasexecuted in a state in which an installing part of the predeterminedequipment was touched to a region (that is, the periphery) in which nolight shielding pattern made of a resist exists on the principal surfaceof a mask substrate of the photomask. The third problem is solved bythese means.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] (a) in FIG. 1 is a sectional view showing a phase shift mask in arepresentative example of the invention and (b) in FIG. 1 shows aprojection exposure method using the phase shift mask shown in (a) ofFIG. 1;

[0046] (a) to (e) in FIG. 2A are sectional views every process showingthe manufacturing process of the mask;

[0047] (f) to (j) in FIG. 2B are sectional views every process showingthe manufacturing process of the mask;

[0048] (k) to (m) in FIG. 2C are sectional views every process showingthe manufacturing process of the mask;

[0049] (a) to (e) in FIG. 3A are sectional views every process showingthe manufacturing process of another mask;

[0050] (f) to (i) in FIG. 3B are sectional views every process showingthe manufacturing process of another mask;

[0051]FIG. 4 is a sectional view showing the main part of a mask forshowing an example in which the phase shift mask is applied;

[0052]FIG. 5 is a sectional view showing the main part of a mask forshowing another example in which the phase shift mask is applied;

[0053] (a) to (c) in FIG. 6 are sectional views showing the main part ofa mask for explaining the problem of the phase shift mask;

[0054] (a) to (e) in FIG. 7A are sectional views every process showingthe main part and the manufacturing process of the phase shift maskequivalent to a first embodiment of the invention;

[0055] (f) and (g) in FIG. 7B are sectional views every process showingthe main part and the manufacturing process of the phase shift maskequivalent to the first embodiment of the invention;

[0056]FIG. 8 is a graph showing an optical absorption characteristic ofphotoresist material;

[0057] (a) to (e) in FIG. 9A are sectional views every process showingthe main part and the manufacturing process of a phase shift maskequivalent to a second embodiment of the invention;

[0058] (f) and (g) in FIG. 9B are sectional views every process showingthe main part and the manufacturing process of the phase shift maskequivalent to the second embodiment of the invention;

[0059] (a) to (e) in FIG. 10 are sectional views every process showingthe main part and the manufacturing process of a phase shift maskequivalent to a third embodiment of the invention;

[0060] (a) to (e) in FIG. 11A are sectional views every process showingthe main part and the manufacturing process of a phase shift maskequivalent to a fourth embodiment of the invention;

[0061] (f) to (j) in FIG. 11B are sectional views every process showingthe main part and the manufacturing process of the phase shift maskequivalent to the fourth embodiment of the invention;

[0062] (a) to (e) in FIG. 12 are sectional views every process showingthe main part and the manufacturing process of a phase shift maskequivalent to a fifth embodiment of the invention;

[0063] (a) and (b) in FIGS. 13 are plans showing the main part of aphase shift mask according to the invention;

[0064] (a) and (b) in FIG. 14 are plans showing a pattern such as acharacter, a symbol and a mark provided to the phase shift maskaccording to the invention;

[0065] (a) in FIG. 15 is a plan showing the main part of a phase shiftmask equivalent to a sixth embodiment of the invention, (b) in FIG. 15is a sectional view showing the main part and a state in which the maskis installed in equipment, and (c) in FIG. 15 is a side view showing themask;

[0066]FIG. 16 is a sectional view showing the main part of a mask forexplaining the problem of the phase shift mask;

[0067]FIG. 17 is a schematic drawing showing the outline of lithographyequipment used in the invention;

[0068]FIG. 18 is a plan showing the main part and a mask pattern layoutequivalent to a seventh embodiment of the invention;

[0069] (a) in FIG. 19 is a plan showing the main part and the layout ofan electronic circuit pattern equivalent to an eighth embodiment of theinvention and (b) in FIG. 19 is a plan showing a phase shift mask forthe electronic circuit pattern;

[0070] (a) in FIG. 20 is a plan showing a phase shift mask equivalent toa-ninth embodiment of the invention, (b) in FIG. 20 is a plan showing abinary mask, and (c) in FIG. 20 is a plan showing a pattern formed byprinting;

[0071] (a) to (d) in FIG. 21 are sectional views every process showingthe main part and the manufacturing process of a semiconductor memorycircuit equivalent to a tenth embodiment of the invention;

[0072] (a) and (b) in FIG. 22 are plans showing the main part forexplaining a circuit layout pattern in the semiconductor memory;

[0073] (a) to (d) in FIG. 23 are sectional views every process showingthe main part and the manufacturing process of a semiconductor logicalcircuit equivalent to an eleventh embodiment of the invention; and

[0074]FIG. 24 is a plan showing the main part of a phase shift maskequivalent to a twelfth embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0075] Before the invention is detailedy described, the meaning of termsin the invention is as follows. 1. A device face means a principalsurface of a semiconductor wafer and a device pattern corresponding toplural semiconductor chip regions is formed on the surface byphotolithography. 2. A semiconductor integrated circuit wafer (asemiconductor integrated circuit substrate) or a semiconductor wafer (asemiconductor substrate) means a silicon monocrystalline substrate(generally substantially flat and circular) used for manufacturing asemiconductor integrated circuit, a sapphire substrate, a glasssubstrate, other insulating, conductive or semiconductor substrates anda their composite substrate. 3. An organic spin-on-glass (SOG) filmmeans an insulating film formed by dissolving polymeric resin in whichvarious organic functional groups are generally bonded to a siloxanepolymer or a copolymer with another monomer in a solvent and applying itso a substrate by spinning. The organic SOG film is generallycharacterized in that as it is more hardly cracked after a cure,compared with an inorganic SOG film, it can be formed with it thicker.As the organic film may be formed by chemical vapor deposition (CVD), itis called only an organic siloxane insulating film in that case. 4. Anetching stopper means the one the etching selection ratio of an etchedfilm to an etching stopper film of which is 4 or more in principle (thatis, in case the etching selection ratio of A to B is X, the etching rateof A is X and the etching rate of B is 1). An applied stopper film andothers are included in the etching stopper film. 5. A masking layergenerally means a resist film, however, it also includes an inorganicmask and a non-photosensitive organic mask. 6. “Light shielding” used ina light shielded region, a light shielding film and a light shieldingpattern means a case provided with an optical characteristic that lightsmaller than 40% (30% in a narrow sense) of exposure light radiated onthe region is transmitted. In the meantime, “transparent” means a caseprovided with an optical characteristic that light exceeding 60% (90% ina narrow sense) of exposure light radiated on a region is transmitted.7. A photoresist pattern means a film pattern acquired by patterning aphotosensitive organic film by photolithography. This pattern includes amere resist film having no aperture. 8. The pattern face of a mask isclassified into an integrated circuit pattern formation region: a regionin which an integrated circuit pattern to be printed is arranged, apellicle covered region: a region covered with a pellicle, an integratedcircuit pattern peripheral region: a pellicle covered region except theintegrated circuit pattern formation region, a peripheral region: anexternal region not covered with a pellicle, a peripheral inner region:an inner region in which an optical pattern is formed in the peripheralregion and a peripheral outer region: a region used for vacuumabsorption and others in the other peripheral region. 9. Ultravioletrays are classified in the field of a semiconductor into ultravioletrays in case the wavelength is between approximately 50 nm andapproximately 400 nm, near ultraviolet rays in case the wavelength is300 nm or more, far ultraviolet rays in case the wavelength is between200 nm and 300 nm and vacuum ultraviolet rays in case the wavelength isbelow 200 nm. In main embodiments of the invention, vacuum ultravioletrays the wavelength of which is below 200 nm is used, however, it needscarcely be said that in case a change described in a second embodimentis made, far ultraviolet rays by a KrF excimer laser the wavelength ofwhich is between 200 nm and 250 nm can be also applied. The principle inthe invention can be similarly applied with a shorter wavelength regionof ultraviolet rays the wavelength of which between 50 nm and 100 nm.10. When mask materials are called “metal”, they mean a compound ofchromium, chromium oxide and other metal and include a simple substanceincluding a metallic element, a compound and a complex respectivelyhaving light shielding action in a wide sense. 11. Levenson type phaseshift mask means one type of a phase shift mask to acquire a vivid imageby interference by alternately inverting the phase of adjacent aperturesseparated by a light shielded region.

[0076] The following various embodiments are respectively divided intoplural sections if necessary, however, except a specified case, thesections are not unrelated and one section is a part of the others or isa transformed example, the detailed description and the supplementarydescription of all. In the following various embodiments, in case thenumber of elements (including the number of pieces, a numerical value,quantity and a range) is referred, the invention is not limited to thespecific number except a specified case and a case that the number ofelements is clearly limited to a specific number and the number ofelements may be also larger or smaller than the specific number.Further, in the following various embodiments, it need scarcely be saidthat a component (including an element step) is not necessarilyessential except a specified case and a case in which the component isclearly considered to be essential. Similarly, in the following variousembodiments, when the form and the positional relation of a componentand others are referred, a form and others substantially close to orsimilar to the form and others are included except a specified case anda clearly different case. This is also similar as to a numerical valueand a range.

[0077] In the invention, a semiconductor integrated circuit includes notonly the one formed on a semiconductor or insulator substrate such as asilicon wafer and a sapphire substrate but the one formed on a glass orother insulating substrate such as a thin film transistor (TFT) and asupertwisted nematic (STN) liquid crystal except a case in whichdifferent material is specified.

[0078] Referring to the drawings, various embodiments of the inventionwill be described in detail below.

[0079] First Embodiment

[0080] (a) to (e) in FIG. 7A and (f) and (g) in FIG. 7B are sectionalviews every process showing the main part for explaining a method ofmanufacturing a phase shift mask equivalent to one embodiment of theinvention.

[0081] First, as shown in (a) of FIG. 7A, a phase shifter 702 is formedon the flat principal surface of a quartz glass substrate (blanks) 701.The thickness d is set so that d=λ/{2(n−1)) when the wavelength ofexposure light is λ and the refractive index of the shifter 702 to thewavelength of exposure light is n. The shifter 702 is formed by SiO_(x)by sputtering and is not limited to this. Another film that transmitsexposure light and is uniform in the thickness and the refractive indexcan be also used. Particularly, a film made of SnO_(x) and TiO_(x) andhigh in the refractive index is desirable because it can be formedthinly and afterward resist light shielding pattern formation isfacilitated. When the refractive index of the film is 1.6 or more, theeffect of the thickness appears. As a conductive film is not influencedby the increase of charges when the following resist is written by EB,it is desirable that the shifter itself, or at least the surface or therear surface is conductive. An ITO film or others is suitable for aconductive film provided to the surface or the rear surface of theshifter. To enhance the durability, after the shifter 701 is deposited,heating processing is executed, however, the set thickness d isequivalent to the thickness after the heating processing. As heatingprocessing, baking at 200° C. for 30 minutes is performed, however, theinvention is not limited to this.

[0082] As the thickness of the shifter that determines a phase angle isimportant, the thickness is measured after film formation includingheating processing and in case the thickness is not within referencevalues, the shifter is removed and a shifter is formed again. Theallowable value of the dispersion of the thickness is approximately 1%though it depends upon the dimension and required dimension accuracy. Asthe shifter 702 is deposited on the flat principal surface, thethickness easily becomes uniform and as a problem that a phase angle(the thickness) varies every dimension by micro loading effect inetching does not also occur, high resolution and dimension accuracy canbe easily acquired. In this embodiment, for a method of forming theshifter, sputtering is used, however, CVD and an application formationmethod can be also used. Particularly, the application formation methodis characterized in that it is excellent in the uniformity of thethickness and in this case, the shifter can be also formed at theuniformity of 0.2%. This is high accuracy equivalent to approximately0.1 degree in terms of phase angle shift. The defect (a pin hole defectand a foreign matter defect) of the phase shifter is inspected and incase a defect is detected, the shifter is reproduced. As a measure for adetect to be a phase defect can be taken at an initial stage, thecontrol of a process is facilitated.

[0083] Next, as shown in (b) of FIG. 7A, an EB resist 703 is applied tothe shifter 702 and a desired pattern is written by EB (704). In casethe shifter 702 is not conductive, a water soluble conductive film isformed on the resist 703 and a countermeasure against the increase ofcharges in writing by EB is taken. When such a countermeasure is nottaken, the misregistration of a written pattern is caused because of theincrease of charges. In this embodiment, as the conductive film isformed, no misregistration by the increase of charges is not caused. Itis found for the conductivity required to prevent the increase ofcharges that when the sheet resistance is 50 MΩ/cm² or less, sufficienteffect is acquired.

[0084] Next, as shown in (c) of FIG. 7A, a resist pattern 705 is formedby development and afterward, as shown in (d) of FIG. 7A, the shifter702 is processed by etching using the resist pattern 705 as a mask.

[0085] Next, as shown in (e) of FIG. 7A, the resist 705 is removed and ashifter pattern 706 is formed on the flat principal surface of thequartz glass substrate 701. At this time, the side at the end of theshifter pattern 706 is tapered. The cone angle θ is approximately 60degrees. A chipped defect and a left defect in the phase shifter pattern706 are inspected using an edge detection method. In this process, asthe defect of the shifter can be inspected by the edge detection methodbecause light shielding materials do not surround the shifter pattern706, phase defect inspection simple and high in detection accuracy canbe made.

[0086] Afterward, as shown in (f) of FIG. 7A, an EB resist 707 isapplied and a desired light shielding pattern is written by EB (708). Atthe time of the exposure, the formation of a conductive film to preventthe increase of charges is also effective as in writing the shifterpattern 706. In this embodiment, the conductive film (not shown) thesheet resistance of which is 30 MΩ/cm² is deposited on the resist 707.As no underlayer is required to be etched afterward, the resistance ofthe EB resist 707 to etching is not required to be minded and whenresist materials excellent in covering difference in a level (orirregularities) at the edge of the shifter by the quantity and high indimension accuracy on the surface having difference in a level areselected, the dimension accuracy of the mask can be enhanced. To acquirehigh dimension accuracy in a location having difference in a level, itis desirable that resist material that can be processed so that thesectional form is approximately perpendicular instead of the form of askirt is used. Actually, in this embodiment, a resist having theperpendicular sectional form of approximately 90 degrees is used. Asthis EB resist also functions as light shielding materials from exposurelight in printing, the materials are required to absorb exposure lightstrongly.

[0087] The EB resist 707 and the EB resist 703 used in the process shownin (b) of FIG. 7a for forming the phase shifter pattern may be also madeof the same materials, however, as at least EB resist 707 is developedand used for the light shielding pattern in printing, the resistance toetching is not required to be minded as described above and the resist707 is required to be made of materials that have a property that theend is easily processed so that the end is sharp and substantiallyperpendicular and can shield from exposure light in printing. That is,the EB resists 703 and 707 had better be made of different materialsaccording to the used purpose.

[0088] Based upon the result of various experiments performed by theseinventors, in this embodiment, photoresist materials mainly includingnovolac resin are used for the resist 707. It is found that as thenovolac resin particularly strongly absorbs ArF exposure light havingthe wavelength of 193 nm as shown in FIG. 8 showing the result ofmeasuring optical absorption characteristics to the wavelength ofradiated light, the resin functions as sufficient light shieldingmaterial when printing is performed by exposure using an ArF excimerlaser. Resin having a benzene ring such as phenol resin which is notlimited to novolac resin is small in the degree of the absorption of KrFexposure light having the wavelength of 248 μm and others, however, thedegree of absorption of ArF exposure light is remarkably large andtherefore, the resin is favorable for ArF beam shielding material. Thenovolac resin and the phenol resin are organic materials themselves,dielectric materials and also, high resistance materials.

[0089] As the resist including a benzene ring has a property that theresist strongly absorbs light having the wavelength of 100 to 200 nm,100 to 200 nm is favorable for the wavelength of exposure light inprinting. The absorbancy of a resist is expressed as an extinctioncoefficient (an imaginary part of a complex refractive index) and it isdesirable from relationship described later between the thickness and anOD value that the absorbancy is 0.5 or more, possibly 1.0 or more. Inthis embodiment, material the extinction coefficient of which is 1.0 isused. When the light shielding film is too thin, light shieldingperformance is not enough and when it is too thick, a problem that thetransmissivity of an aperture varies depending upon the dimension of theaperture by the effect of the side wall of the resist pattern is caused.When the transmissivity of exposure light is lowered up to 3 or more inthe terms of an OD value in a location in which the resist is thin inthe vicinity of an edge having difference in a level, the resistfunctions as sufficient light shield material. When the OD value is 4 ormore, the effect of the phase of light slightly transmitted in the lightshielding part does not cause no problem and when the OD value is 5 ormore, no light is transmitted. The OD value means a value expressed aslog 10 (Iout/Iin) when incident light is Iin and transmitted light isIout. It is desirable in view of critical dimension accuracy that theupper limit of the thickness d′ at the edge of an aperture of the resistis the three times of the minimum aperture width w or less, that is, 3 wor less. When the wavelength of exposure light is λ and the refractiveindex of exposure light in the phase shifter is n, the lower limit ofthe thickness is λ/{2(n−1)}. The thinner resist is not enough in thedensity of light shielding. It is desirable based upon the result ofactual printing that 0.2 μm or more is practically secured.

[0090] As the edge of the shifter 706 is tapered as described above, thecoverage of the resist is satisfactory and as the variation of thethickness is relatively small, resist pattern dimension accuracy ishigh. As the variation of the thickness of the resist has an effect in alarge range though no pattern directly crosses a part having differencein a level, the effect of the tapered shape is large. In this case, thecone angle θ is 60 degrees, space for registration is provided and theresist made of light shielding materials is limited so that the resistcovers the taped part. The optimum cone angle is determined based upon apattern smallest rule and the alignment accuracy of the shifter and theresist pattern. It can be verified based upon the result of variousexperiments that a cone angle of 45 degrees or more is desirable.

[0091] Afterward, as shown in (g) of FIG. 7B, development is performedand a light shielding resist pattern 709 is formed. Further, heating orthe radiation of deep UV (DUV) or both processing is executed.Resistance to exposure light in the printing of the resist lightshielding material 709 is enhanced by executing this processing.

[0092] A phase error of the phase shift mask equivalent to thisembodiment is within 0.5 degree, the controllability of a phase isextremely high and as the phase shift mask has no dependency upon thedimension, the dimension accuracy and the resolution in pattern printingare high. The resist light shielding material 709 is in contact with theblanks 701 and the phase shifter 706 in large area and a defect such asthe peeling of a pattern is not caused. Further, as the number of themanufacturing processes is small, the mask manufacturing yield is highand TAT is short. Further, the reflectivity of exposure light on thesurface of the light shielding material 709 is 6% on the side of the airand is 1% on the side of the blanks, can be much smaller than thereflectivity of Cr on the surface of which Cr oxide described inrelation to FIG. 16 is deposited and to which reflection preventionprocessing is applied and the deterioration of printing resolutionperformance due to a flare in a lens caused by the reflected light canbe prevented. The reflectivity of Cr to which the reflection preventionprocessing is applied is 13% on the side of the air. The difference isincreased in an inclined part caused because of difference in a level ofthe substrate.

[0093] In this embodiment, the phase 0 and the phase 7 the phases ofwhich are inverse by 180 degrees are formed by processing the shifter702 formed on the flat surface of the blanks 701, however, it is alsoeffective to adjust phase difference by etching a part of the blanks inaddition to this shifter pattern. At this time, when the wavelength ofexposure light is λ, the refractive index of exposure light in theblanks is n0, the refractive index of exposure light in the shifter isn1 and the thickness of the shifter is d1, the phase is inverted byetching the blanks by the depth of “λ/{2(n0−1)}−(n1−1)d1/(n0−1)” andwhen printing is performed using the mask, the highest resolution isacquired. As in this method, the phase can be adjusted after the shifteris formed, it is effective to further enhance the mask manufacturingyield.

[0094] Second Embodiment

[0095] Referring to (a) to (e) of FIG. 9A and (f) and (g) of FIG. 9Bshowing the manufacturing process of a mask, a second embodiment of theinvention will be described below.

[0096] First, as shown in (a) of FIG. 9A, an interference control layer802 is formed on the flat principal surface of a quartz glass substrate(blanks) 801 and afterward, a shifter 803 is formed on the interferencecontrol layer 802. The interference control layer 802 is a transparentfilm that transmits exposure light and the refractive index n′ ofexposure light in the film is larger than that of the quartz glasssubstrate and is the same as or smaller than the refractive index n ofthe shifter 803. When the wavelength of exposure light is λ, it isdesirable that the thickness d′ of the interference control layer 802meets an expression, sin(2πn′(d′+λ/2(n−1)/λ)=sin(2πn′d′/λ). On thiscondition, the multiple interference of exposure light caused betweenthe blanks 801 and the shifter 803 is equal between the phase 0 and thephase 7 and the dimension accuracy is enhanced. The interference controllayer can be also made of the same material as the shifter 803, however,preferably the interference control layer having such etching selectionratio as the interference control layer functions as an etching stopperin processing the shifter 803 and having the substantially equalrefractive index is optimum. Further, as the interference control layeris not influenced by the increase of charges in the following writing aresist by EB when the interference control layer is conductive, it issuitable. In this case, TiO_(x) is used for the interference controllayer 802 and TiO_(x) is also used for the shifter 803, however, it isalso effective to use different materials such as SnO_(x) for theinterference control layer 802 and TiO_(x) for the shifter 803 andenhance processing accuracy.

[0097] The thickness d of the shifter 803 is set to λ/{2(n−1)} when thewavelength of exposure light is λ and the refractive index of exposurelight in the shifter 803 is n. As a film made of TiO_(x) and having ahigh refractive index is used for the shifter 803, the thickness d canbe reduced and the afterward formation of a resist light shieldingpattern is facilitated. To enhance the durability, after theinterference control layer 802 and the shifter 803 are deposited,heating processing is applied, however, the thickness after the heatingprocessing is set as the thickness d. In this case, for heatingprocessing, baking at 200° C. for 30 minutes is performed, however, theinvention is not limited to this. As the thickness of the shifter 803 isimportant to determine a phase angle, the thickness is measured afterthe layer is formed including heating processing and in case a value ofthe thickness of the shifter is not within reference values, the shifteris removed and is formed again. The allowable values of the dispersionof the thickness vary depending upon the dimension and requireddimension accuracy, however, they are approximately 1%. As in the firstembodiment, as the shifter 803 is deposited on the flat surface of atransparent plate, the thickness easily becomes uniform and as a problemthat a phase angle (the thickness) varies every dimension by microloading effect in etching does not occur, high resolution and dimensionaccuracy can be easily acquired in this case, the shifter 803 is formedby sputtering, however, CVD and an application formation method can bealso used.

[0098] Next, as shown in (b) of FIG. 9A, an EB resist 804 is formed onthe shifter 803 by application and a desired shifter pattern is writtenby EB (805). In case the shifter 803 is not conductive, a water solubleconductive film is formed on the resist 804 and a countermeasure for theincrease of charges in writing by EB is taken. When such acountermeasure is not taken, a written pattern is displaced because ofthe increase of charges. In this embodiment, as the conductive film isformed, no misregistration of a written position is caused due to theincrease of charges.

[0099] Next, as shown in (c) of FIG. 9A, development is performed, aresist-pattern 806 is formed and afterward, as in (d) of FIG. 9A, theshifter 803 is processed by etching using the resist pattern 806 as amask. As described above, in case SnO_(x) is used for the interferencecontrol layer 802 and TiO_(x) is used for the shifter 803, it is foundthat the interference control layer 802 functions as an etching stopperby etching using CF gas for example, the shifter 803 can be processedprecisely, the surface of the blanks 801 can be prevented from beingetched and the surface of the blanks is not influenced by the distortionof processing and others.

[0100] Further, as shown in (e) of FIG. 9A, the resist 806 is removedand a shifter pattern 807 is formed on the interference control layer802. A defect that the phase shifter chips and a defect that the phaseshifter is left are inspected by an edge detection method. As lightshielding material does not surround the shift pattern, the defect ofthe shifter can be inspected by the edge detection method and simplephase defect inspection having high detection accuracy can be executed.

[0101] Afterward, as shown in (f) of FIG. 9B, an EB resist 808 isapplied and writing is performed by EB (809) using a desired lightshielding pattern. It is also effective in exposure to form a conductivefilm for preventing the increase of charges as when the shifter patternis written. In this embodiment, a conductive film (not shown) having thesheet resistance of 40 MΩ/cm² is deposited on the resist 808.

[0102] As afterward, the substrate is not required to be etched, theresistance to etching of the EB resist 808 is not required. When aresist excellent in the coverage of a part having difference in a leveland having high dimension accuracy on the substrate having difference ina level by the quantity can be selected, the dimension accuracy of themask can be enhanced. To acquire high dimension accuracy in a parthaving difference in a level, a resist the section of which isperpendicular and which is not in the shape of a skirt has only to beused. As the EB resist 808 also functions as exposure light shieldingmaterial in printing, it is required to be made of material thatstrongly absorbs exposure light in printing. I this embodiment, a resist(itself is dielectric material, high resistance material and alsoorganic material) acquired by mixing dye of light having the wavelengthof 248 nm with novolac resin is used. The resin functions as lightshielding material enough for KrF exposure light having the wavelengthof 248 nm in printing by the effect of the dye. Generally, when strongdye is added, the resolution performance of a resist is extremelydeteriorated, however, this resist is an EB resist and as the added dyeis for the wavelength of 248 nm, resolution enough to produce the maskcan be acquired. It is desirable that the absorbancy of a resist is 0.5or more, possibly 1.0 or more in the terms of an extinction coefficientin consideration of relation described later between the thickness andan OD value. In this embodiment, material the extinction coefficient ofwhich is 0.6 is used. When the thickness is too thin, light shieldingperformance becomes insufficient and when the thickness is too thick, aproblem that the transmissivity in an aperture varies depending upon thedimension of the aperture by the effect of a resist pattern side walloccurs. When the transmissivity of exposure light in a part having athinner resist in the vicinity of the edge having difference in a levelis lowered up to 3 or more in the terms of an OD value, the resistfunctions as sufficient light shielding material. When its OD value is 4or more, the effect of the phase of light slightly transmitted in alight shielding part does not come into question and when its OD valueis 5 or more, transmitted light has no effect. As the shifter 807 ismade of TiO_(x) the refractive index of which is high, there is littledifference in a level by the shifter pattern and the coverage of theresist is enhanced, the resist to which dye is added can acquiresufficient resolution performance.

[0103] Afterward, as shown in (g) of FIG. 9B, development is performedand a light shielding resist pattern 810 is formed. Further, heatingprocessing, DUV radiation or both processing is executed. The resistanceto exposure-light of the resist light shielding material 810 in printingis enhanced by executing this processing.

[0104] The phase error of the phase shift mask in this embodiment iswithin 0.5 degree, phase controllability is extremely high and as thephase shift mask has no dependency upon dimension, dimension accuracyand resolution when pattern printing is performed by KrF exposure lightare high. The shifter having higher refractive index than that of blanksis used, however, there is no bad effect of multiple inference causedbetween the shifter and the blanks and there is no dimensionaldispersion between the phase 0 and the phase π which are inverse by 180degrees. The resist light shielding material 810 is in contact with theinterference control layer 802 and the phase shifter 807 in large areaand no defect such as the peeling of a pattern occurs. Particularly,adhesion between TiO_(x) used for the interference control layer 802 andthe phase shifter is satisfactory. Further, as the number ofmanufacturing processes of the phase shift mask is similarly small tothat in the first embodiment, the manufacturing yield is also high andTAT is also short. Further, the reflectivity of exposure light on thesurface of the light shielding material 810 is 6% on the side of theair, is 1% on the side of the blanks, can be much lower than thereflectivity (15% on the side of the air) of Cr on the surface of whichCr oxide is deposited and to which reflection prevention processing isapplied and the deterioration of the resolution performance in printingdue to a flare in a lens caused by the reflected light can be prevented.If the section of the edge of the shifter 706 is taped, the secondembodiment is effective as in the first embodiment.

[0105] Third Embodiment

[0106] Referring to FIG. 10 showing the manufacturing process of a mask,a third embodiment of the invention will be described below.

[0107] First, as shown in (a) of FIG. 10, a photosensitive shifter 902is formed on the flat principal surface of a quartz glass substrate(blanks) 901. For the material of the photosensitive shifter, organicSOG to which an acid generator is added is used. For the acid generator,triphenylsulfonium triflate (TPS) is used, however, the invention is notlimited to this. The photosensitive shifter is also not limited toorganic SOG and has only to be material that transmits exposure light,has resistance to exposure and has photosensitivity in writing a mask.As the refractive index of exposure light (wavelength: 193 nm) in thephotosensitive shifter 902 is 1.58 and is close to 1.56 which is therefractive index of quartz glass, the photosensitive shifter 902 isdirectly formed on the flat principal surface of the blanks 901,however, when an interference control film is formed as in the secondembodiment in case there is difference between both refractive indexes,multiple interference caused in the shifter can be reduced and theinterference control layer is effective to enhance dimension accuracy.When a conductive film is formed on the blanks 901, there is effect thatthe increase of charges is prevented as in the second embodiment whenthe photosensitive shifter is next written. In this case, thephotosensitive shifter 902 is formed by application, however, anothermethod such as CVD may be also used. However, an application formationmethod has characteristics that it is simple and a defect is hardlycaused. For another applied film, an acid generator is added to methylsilazane. After the shifter is applied, heating processing at 120 isexecuted. The inspection of a defect is performed after the shifter isformed and it is verified that there are no pin hole defect and noforeign matter defect. In case these defects are found, the shifter isremoved and a new shifter is formed again.

[0108] The thickness d of the shifter 902 is set to a value corrected sothat λ/{2(n−1)} after densifying baking described later. The wavelengthof exposure light is λ and the refractive index of exposure light in theshifter 902 after the densifying baking is n.

[0109] Next, as shown in (b) of FIG. 10, the photosensitive shifter 902is directly written by EB with a predetermined pattern (903). A watersoluble conductive film (not shown) is formed on the photosensitiveshifter 902 for a countermeasure for the increase of charges in writingby EB. If such a countermeasure is not taken, the misregistration of awritten pattern is caused by the increase of charges. In thisembodiment, as the conductive film is formed, no misregistration of awritten pattern is caused by the increase of charges.

[0110] Next, as shown in (c) of FIG. 10, development is performed and ashifter pattern 903 is formed. Afterward, to enhance resistance toexposure light and prevent weathering, heating processing is applied tothe shifter pattern 904. In this case, for heating processing, baking at250° C. for 30 minutes is performed, however, the invention is notlimited to this. As the temperature is raised, the resistance isenhanced. As the thickness d of the shifter 904 determines a phase angleand is important, the thickness is measured after the heating processingand if the thickness is not within reference values, the shifter isremoved and a new shifter is formed again. The allowable values of thedispersion of the thickness vary depending upon the dimension andrequired dimension accuracy, however, the allowable value isapproximately 1%. As the shifter is deposited on the flat surface, thethickness easily becomes uniform and as no problem that a phase angle(the thickness) varies every dimension by micro loading effect inetching occurs, high resolution and high dimension accuracy can beeasily acquired.

[0111] Afterward, a defect that the phase shifter chips and a defectthat the phase shifter is left are inspected by an edge detectionmethod. As the light shielding material does not surround the shifterpattern, the defect of the shifter can be inspected by the edgedetection method and simple phase defect inspection having highdetection accuracy can be performed. As described above, a phase shifterpattern free of a defect and excellent in phase controllability can beformed in only processes for application, baking, exposure anddevelopment without an etching process.

[0112] Afterward, as shown in (d) of FIG. 10, a resist 905 is appliedand is written by EB (906) with a desired light shielding pattern. It isalso effective to form a conductive film for preventing the increase ofcharges in exposure as when the shifter pattern 904 is written. In thisembodiment, a conductive film (not shown) having the sheet resistance of40 MΩ/cm²is deposited on the resist 905. As afterward, the substrate isnot required to be etched, the strictness of the resistance to etchingof the EB resist 905 is not required and when resist material excellentin the coverage of a part having difference in a level and having highdimension accuracy on the substrate having difference in a level by thequantity is selected, the dimension accuracy of the mask can beenhanced.

[0113] As the EB resist 905 also functions as exposure light shieldingmaterial in printing, it is required to be made of material thatstrongly absorbs exposure light in printing. In this embodiment, aphotoresist mainly made of phenol resin is used, however, the extinctioncoefficient to exposure light (wavelength: 193 nm) of the material is0.9 and the material functions as sufficient light shielding material inprinting using ArF exposure light. It is desirable that the absorbancyof the resist is 0.5 or more, possibly 1.0 or more in terms of anextinction coefficient in consideration of relation between thethickness and an OD value described later. When the thickness is toothin, light shielding performance becomes insufficient and when thethickness is too thick, a problem that the transmissivity of an aperturevaries depending upon the dimension of the aperture by the effect(waveguide effect) of the resist pattern side wall occurs. When thetransmissivity of exposure light is lowered up to 3 or more in the termsof an OD value in a location in which the resist is thin in the vicinityof an edge having difference in a level, the resist functions assufficient light shield material. When the OD value is 4 or more, theeffect of the phase of light slightly transmitted in the light shieldingpart causes no problem and when the OD value is 5 or more, transmittedlight has no effect.

[0114] In this embodiment, the EB resist is used, however, a resist forexposure such as KrF and i may be also used and a laser and others canbe also used for writing. For writing by a laser, resolution is slightlyinferior to that in writing by EB, however, writing by a laser hascharacteristics that a problem of the increase of charges is solved andthe effect of heat in exposure is reduced.

[0115] Afterward, as shown in (e) of FIG. 10, development is performedand a light shielding photoresist pattern 907 is formed. Further,heating or the radiation of deep UV (DUV) or both processing isexecuted. Resistance to exposure light in the printing of the resistlight shielding material 907 is enhanced by executing this processing.

[0116] A phase error of the phase shift mask equivalent to thisembodiment is within 0.5 degree, the controllability of a phase isextremely high and as the phase shift mask has no dependency upon thedimension, the dimension accuracy and the resolution in pattern printingby ArF exposure light are high.

[0117] The resist light shielding material 907 is in contact with thephase shifter 904 and the substrate 901 in large area and a defect suchas the peeling of a pattern is not caused. As the number of themanufacturing processes of the mask is much smaller, compared with thatin the embodiment and in addition, the manufacturing process includesonly processes for application, baking, exposure, development andinspection respectively hardly causing a defect, the mask manufacturingyield is high and TAT is short.

[0118] Further, the reflectivity of exposure light on the surface of thelight shielding material is 6% on the side of the air and is 1% on theside of the blanks, can be much smaller than the reflectivity (18% onthe side of the air) of Cr on the surface of which Cr oxide is depositedand to which reflection prevention processing is applied and thedeterioration of printing resolution performance due to a flare in alens caused by the reflected light can be prevented. The difference isincreased in an inclined part caused because of difference in a level ofthe substrate.

[0119] Fourth Embodiment

[0120] Referring to (a) to (e) of FIG. 11A and (f) to (j) of FIG. 11Brespectively showing the manufacturing process of a mask, a fourthembodiment of the invention will be described below.

[0121] First, as shown in (a) of FIG. 11A, a resist 1002 is applied onblanks 1001 by a normal method, a desired shifter pattern is written byEB (1003), is developed and as shown in (b) of FIG. 11A, a resistpattern 1004 is formed.

[0122] Afterward, as shown in (c) of FIG. 11A, the exposed surface ofthe transparent plate (the blanks) 1001 is partially etched inpredetermined depth and a concavity, that is, a groove or a depressionis formed.

[0123] Next, as shown in (d) of FIG. 11A, the resist 1004 is removed bya normal method and difference in a level composed by a concavity and/ora convexity is made on the principal surface of the blanks 1001. Thedifference in a level, that is, the difference in a level between aconvexity 1005 and a concavity 1006 in (d) of FIG. 11A is measured witha meter for measuring difference in a level or an atomic forcemicroscope (AFM) and is converted to phase difference or phasedifference is directly measured by an interferometer. In case phasedifference between wavelengths of exposure light is in a desired rangeof 180 degrees, processing proceeds to a process shown in (i) of FIG.11B. In this case, the range is +1.5 degrees. The value varies dependingupon required dimension accuracy and as high dimension accuracy isrequired, the range becomes narrow. When phase difference is outside thedesired range, processing proceeds to the following process.

[0124] In this embodiment, as phase difference is 165 degrees, theresist 1007 is applied again as shown in (e) of FIG. 11A, a shifterpattern is exposed (1008), is developed and as shown in (f) of FIG. 11B,a resist pattern 1009 is formed.

[0125] Afterward, as shown in (g) of FIG. 11B, the blanks 1001 is etchedagain. Next, the resist 1009 is removed and as shown in (h) of FIG. 11B,blanks having phase shift patterns 1010 and 1011 is formed.

[0126] Phase difference to exposure light between two surfaces 1010 and1011 shown in (h) of FIG. 11B is measured and it is varied that thephase difference is in a desired range of 180 degrees. Afterward, phasedefect inspection is performed in an edge detection mode. As no defectis detected, processing proceeds to the next process, however, in case adefect is detected, it is corrected using FIB method or when thecorrection of the defect is difficult, the two surfaces are producedagain. This method has a characteristic that in a relatively initialprocess, phase defect inspection can be performed by a method havinghigh inspection accuracy called the edge detection method. Afterward,cleaning processing is performed.

[0127] Next, as shown in (i) of FIG. 11B, an EB resist 1012 is appliedand the exposure of a pattern for forming a part for light to beshielded is performed (1013). Afterward, development is performed and asshown in (j) of FIG. 11B, a light shielding pattern 1014 made of theresist is formed.

[0128] As in the first to third embodiments, a water soluble conductivefilm is formed on the EB resist for a countermeasure for preventing theincrease of charges in writing by EB. For a measure for preventing theincrease of charges, a method of forming a conductive film such as ITOunder a resist is also effective in addition. As the effect of theincrease of charges can be also avoided in measuring the dimension usingSEM and others in case the conductive film is left, high precision QCcan be performed.

[0129] As the resist 1014 also functions as light shielding materialfrom exposure light in printing, it is required to be made of materialthat strongly absorbs exposure light in printing. In this embodiment, aphotoresist mainly made of novolac resin is used. As novolac resinstrongly absorbs ArF exposure light having the wavelength of 193 nm, itfunctions as sufficient light shielding material in printing by ArFexposure light. For other materials, there are polyaniline resin andothers. As polyaniline resin has conductivity, charges hardly increasein writing by EB and it is also effective in the sense. In casepolyaniline resin is used, the application of a water soluble conductivefilm can be omitted.

[0130] In this embodiment, as a process for depositing Cr and a processfor etching Cr are not included, the number of the manufacturingprocesses of the mask can be reduced and as the high quality depositionof Cr is not required, the manufacturing cost can be reduced by thequantity. Further, the reflectivity of exposure light on the surface oflight shielding material is 6% on the side of the air, is 1% on the sideof the blanks, is much smaller than the reflectivity of Cr on thesurface of which Cr oxide is deposited and to which reflectionprevention processing is applied and the deterioration of printingresolution performance due to a flare in a lens caused by the reflectedlight can be prevented.

[0131] In this embodiment, the phase difference of 180 degrees is givenbetween a phase 0 and a phase π by etching only the side of the phase πof the blanks, however, the phase difference of 180 degrees may be alsogiven between both phases according to a method of also etching thephase 0 in addition to the phase π.

[0132] Fifth Embodiment

[0133] In the first to fourth embodiments, the shifter andirregularities on the blanks are required to be accurately positionedbased upon the position of these shifter patterns and a light shieldingpattern is required to be written. However, as the material of theshifter pattern is close to that of the blanks or the same, positioningaccuracy is deteriorated when the shifter pattern, particularly a parthaving difference in a level of it (a boundary and irregularities) ispositioned. Then, a third layer is formed by a metallic film, analignment mark is formed on it beforehand, the mark is detected, and theshifter pattern and the resist light shielding pattern are written.Based upon the third embodiment, referring to process drawings shown inFIG. 12, a fifth embodiment will be described below.

[0134] First, as shown in (a) of FIG. 12, a metal layer 1102 on which analignment reference mark 1103 in writing by EB is formed is formed onthe flat surface of blanks 1101. The metal layer is formed outside apattern printed field. A dielectric film, a high resistance film or anorganic film (for example, a photoresist) is arranged in the center ofthe blanks and the metal layer is arranged outside it. For metal, Cr isused, however, in addition, W, Ti, Mo, MoSi, Ta or WN_(x) can be alsoused. Material the processing of which is easy and in which highcontrast of the reflection of EB is acquired is desirable.

[0135] Next, as shown in (b) of FIG. 12, a photosensitive shifter 1104and a water soluble conductive film 1105 are formed on the photoresistand the metal layer, the shifter pattern is exposed by EB and isdeveloped and as shown in (c) of FIG. 12, a shifter pattern 1106 isformed. When the shifter pattern 1106 is exposed, the reference mark1103 is detected by EB and referring to the position, writing isperformed. As the alignment mark is made of a metal pattern, it can beprecisely detected.

[0136] Afterward, as shown in (d) of FIG. 12, an EB resist 1107 isapplied and a water soluble conductive film 1108 is formed on it.

[0137] Afterward, a light shielding pattern is exposed by EB and asshown in (e) of FIG. 12, a resist pattern 1109 is formed. When the lightshielding pattern is exposed by EB, the reference mark 1103 is detectedby EB and referring to the position, writing is performed by EB. As thereference mark is made of a metal pattern, it can be precisely detected.The shifter pattern 1106 and the resist light shielding pattern 1109 arerelatively aligned using the metal mark 1103. Though three layers arealigned, the alignment accuracy of 50 nm is acquired because alignmentreference mark detection contrast is high. In the meantime, when theresist light shielding pattern is written using the shifter pattern asan alignment reference mark, sufficient contrast is not acquired indetecting the mark, alignment accuracy is 200 nm, further, the mark isdetected by mistake and writing may be disabled.

[0138] In this process, the case in the third embodiment is described,however, in the other embodiments, writing is similarly performed usingthe metal reference mark. As a result, sufficient alignment accuracy canbe acquired. In case the shifter has sufficient conductivity, requiredalignment accuracy can be also acquired using a shifter pattern markinstead of the metal reference mark.

[0139] (a) in FIG. 13 shows the outline when a manufactured mask isviewed from the top. An outer frame 1101 made of metal is formed outsidea pattern printed field region 1110 and in the outer frame region, ashifter pattern and resist light shielding pattern alignment referencemark 1111 and a reticle mark 1103 for making lithography equipmentrecognize a position in which a mask is located and for alignment areformed. Further, an identification mark 1112 for identifying the reticle(the mask) is formed on the metal layer on the outer frame.

[0140] When the reticle mark 1103 is made of metal, it can be preciselydetected even if the position is monitored with light of any wavelength.The reticle mark 1103 is formed by removing a part of the metallic filmof the light shielding outer frame 1101 and exposing a transparent masksubstrate under the metallic film. Therefore, as the contrast of lighttransmitted in the reticle mark 1103 is sufficiently acquired even iflithography equipment using a normal halogen lamp and others fordetecting the position of a mask is used, reticle mark recognitioncapacity can be enhanced. Therefore, a mask and lithography equipmentcan be relatively aligned easily and precisely. According to the resultof review by these inventors, alignment is enabled at the similaraccuracy to a normal photomask.

[0141] Referring to the configuration of lithography equipment, thiswill be described below. FIG. 17 shows an example of reductionprojection lithography equipment used in the various embodiments andexposure light emitted from a light source 1501 of the reductionprojection lithography equipment radiates a mask 1507 via a fly eye lens1502, an aperture for the selection of an illuminator condition 1503,condenser lenses 1504 and 1505 and a mirror 1506. The mask 1507 ismounted in a state in which the principal surface on which a lightshielding pattern is formed (the first principal surface) is directeddownward(on the side of a semiconductor wafer 1509). Therefore, exposurelight is radiated from the side of the rear surface (the secondprincipal surface) of the mask 1507.

[0142] Hereby, a mask pattern written on the mask 1507 is projected onthe semiconductor wafer 1509 which is a sample substrate via aprojection lens 1508. A pellicle 1510 for preventing pattern printingfailure by the adhesion of a foreign matter is provided on the firstprincipal surface of the mask 1507 if necessary.

[0143] The mask 1507 is vacuum-attracted on a mask stage 1512 controlledby mask position control means 1511, is aligned by position detectionmeans 1513, and the center and the optical axis of the projection lensare precisely aligned. The semiconductor wafer 1509 is vacuum-attractedon a sample stage 1514. The sample stage 1514 is mounted on Z stage 1515which can be moved in a direction of the optical axis of the projectionlens 1508, that is, in a direction of the z-axis and further, is mountedon an XY stage 1516. As the Z stage 1515 and the XY stage 1516 aredriven by respective driving means 1518 and 1519 according to a controlinstruction from a main control system 1517, they can be moved in adesired exposure position. The position is precisely monitored as theposition of the mirror 1520 fixed on the Z stage 1515 by a laser lengthmeasuring machine 1521.

[0144] Further, for example, a halogen lamp is used for the positiondetection means 1513. That is, a special light source is not required tobe used for the position detection means 1513 (new technique anddifficult technique are not required to be newly adopted) and normalreduction projection lithography equipment can be used.

[0145] In the meantime, when a reticle mark is made of resist lightshielding material, alignment using the reticle mark is difficult. Thisreason is that generally, light having a longer wavelength than exposurelight cannot be shielded with sufficient contrast.

[0146] A film in a part which comes in contact with the stage of thelithography equipment and a carrier is removed halfway a manufacturingprocess without leaving a light shielding film such as a resist, aphotosensitive shifter or an applied shifter. When a film is required tobe left, the surface may be also covered with a metallic film such as Crso that the surface is not exposed. Hereby, a foreign matter can beprevented from being caused by carriage In case such a measure is nottaken, a foreign matter is caused and a defect in printing may becaused.

[0147] (b) in FIG. 13 shows another example when a mask is viewed fromthe top. Outside a pattern printing field region 1202, a shifter patternand resist light shielding pattern alignment reference mark 1201 and anidentification mark region 1203 for identifying a reticle (a mask) areformed. The alignment reference mark 1201 and the identification markregion 1203 are made of metal. It is desirable that the alignmentreference mark is arranged at least at four corners of a mask to correctdistortion in writing.

[0148] That is, writing is performed monitoring mark at four corners andcorrecting distortion. A mask identification mark 1204 is written on themetal region 1203 with a resist. As a resist is a thin film on the metalthough a resist mark on the blanks is difficult to be identified withnaked eyes, interference occurs in the resist, reflectivity varies andidentification is enabled. However, the identification mark is requiredto be formed in a location which is not in contact with the stage of thelithography equipment and a carriage mechanism. The reason is that asthe mark is made of an organic fragile film, a foreign matter is causedwhen the mark is touched and when a mask according to the invention istreated, care is required.

[0149] The case that the identification mark is formed on the metal by aresist is described above, however, referring to FIG. 14, a method ofdirectly providing an identification mark on the blanks (the quartzglass) will be described below.

[0150] (a) of FIG. 14 shows a mask identification mark by a character2201 RET written with a photoresist on the metal region 1203 shown inFIG. 13, (b) of FIG. 14 shows a mask identification mark written not bya character but by a so-called bar code 2203 and in both cases, pluralphotoresists in the shape of a slit are arranged in parallel at aninterval of 0.5 to 2.0 μm (2202, 2204) or multiple slits are carved onone photoresist at the pitch. Actually, photoresists are written at thepitch of 1.0 μm, however, reflectivity increases by interference effectand they can be sufficiently identified. Particularly, as the se,ting ofa code can be arbitrarily determined in display shown in FIG. 14, theidentification mark can be utilized for extremely detailed managementinformation related to manufacture and is also effective for securityfor preventing the leakage of manufacturing various information.

[0151] Sixth Embodiment

[0152] In a sixth embodiment, an example that a transparent pellicle isarranged on the principal surface of a mask so that a foreign matterdoes not adhere to the pattern formation surface (the first principalsurface) of the mask will be described. The sixth embodiment is similarto the first to fifth embodiments except it. A case that a mask in whicha light shielding pattern made of a metallic film is provided in theperiphery of a mask substrate as the mask described in the fifthembodiment is used will be described below.

[0153]FIG. 15 shows a concrete example of a mask in the sixthembodiment. (a) of FIG. 15 is a plan showing a mask 1301, (b) of FIG. 15is a sectional view showing the main part and a state when the mask 1301is mounted in predetermined equipment, and (c) of FIG. 15 is a sectionalview showing the main and an applied example.

[0154] In the sixth embodiment, a pellicle 1302 is bonded to theprincipal surface (the first principal surface) of the mask 1301 via apellicle sticking frame 1303 and is fixed. The pellicle 1302 is atransparent protective film provided from the principal surface of themask substrate or the principal surface and the rear surface to fixeddistance to prevent a foreign matter from adhering to the patternformation principal surface of the mask 1301. The fixed distance isdesigned in consideration of a foreign matter which adheres to thesurface of the protective film and the printing of a foreign matter onthe surface of a processed material body such as a semiconductor wafer.

[0155] The pellicle 1302 is arranged a pellicle cover region of the mask1301. That is, the pellicle 1302 is arranged so that it covers the wholeintegrated circuit pattern formation region 1304 of the mask 1301 and apart of a metal light shielding pattern 1305 formed in the peripheralinside region.

[0156] In this embodiment, the base of the pellicle sticking frame 1303is bonded and fixed in a state in which the base is directly in contactwith the metal light shielding pattern 1305 in the peripheral insideregion of the mask 1301. Hereby, the pellicle sticking frame 1303 can beprevented from being peeled. In the meantime, when a resist is formed ina position in which the pellicle sticking frame 1303 is attached, theresist is peeled and a foreign matter is caused in attaching ordetaching the pellicle 1302. In this embodiment, as the pelliclesticking frame 1303 is bonded in a state in which it is directly touchedto the light shielding pattern 1305, such a foreign matter can beprevented from being caused. Such effect is also acquired in case thepellicle sticking frame 1303 is bonded and fixed in a state in which itis directly touched to the mask substrate 1301.

[0157] As in the fifth embodiment, as shown in (b) of FIG. 15, noorganic film such a resist exists in a part in which the mask 1301 and avacuum suction stage 1306 of the projection lithography equipment aretouched. In (b) of FIG. 15, the metal film 1305 exists. Hereby, as inthe fifth embodiment, a foreign matter can be prevented from beingcaused due to the peeling and a chip of a resist.

[0158] In this embodiment, a mark pattern 1307 for calibrating aposition is formed in the metal light shielding pattern 1305. The markpattern 1307 for calibrating a position is a pattern for directlydetecting the positional information of a mask from the mask itself whena predetermined pattern is written on the mask using an electron beamwriter. That is, in this embodiment, a pattern is written, correcting(adjusting) a position in which an electron beam for writing a patternin a pattern writing process is radiated by reading the mark pattern1307 on the mask substrate once every seconds when a predeterminedintegrated circuit pattern is formed in an integrated circuit patternformation region of the mask substrate using an electron beam writer.Hereby, pattern writing position accuracy by the electron beam writercan be further enhanced. The reason why such a mark pattern 1307 isprovided is as follows.

[0159] In a normal electron beam writer, processing for writing on amask is executed in decompressed vacuum. For holding a mask in vacuum, amask substrate or a cassette including a mask substrate is pressed on athree-point pin of a mask holder on the moving stage of the electronbeam writer and is mechanically fixed by a pin. In a normal electronbeam writer, to prevent misregistration by the drift of the position ofan electron beam during writing in pattern writing, a mark pattern fordetecting a position attached to the mask holder is detected pluraltimes in writing.

[0160] As a mask substrate on the mask holder (stage) is mechanicallyfixed as described above, relative positional relation between the markpattern on the mask holder and the mask substrate should be fixed,however, actually, slight misregistration may occur between the markpattern and the mask substrate by the shock of the stage moved at highspeed. Therefore, though the position of the mask substrate is read fromthe mark pattern in the electron beam writing process, misregistrationoccurs in a written pattern.

[0161] Then, in this embodiment, the mark pattern 1307 for calibrating aposition is arranged on a mask (a mask substrate) itself and theposition can be directly detected from the mask substrate itself.Hereby, as the misregistration of the mask substrate can be corrected, apattern arrangement error can be reduced. Such a mark pattern 1307 is ina light transmitted region or in a light shielded region and informationis detected by a position detection beam radiated there or based uponthe reflection of detected light. For position detection means, a typeusing an electron beam from an electron beam writer, a type using alaser beam from a laser writer or other type can be used. Particularly,the application of equipment the positional accuracy of which is high isdesirable. A reference number 1308 in FIG. 15 denotes a circuit patternand 1309 denotes a reticle mark showing the position of a mask inlithography equipment.

[0162] As shown in (c) of FIG. 15, an identification mark RETICLE-A of abuilt mask is written on the side wall of the frame 1303 of the pellicle1302 attached to the metallic film 1305 on the mask substrate 1301 viaan adhesive and others. Hereby, the area of the surface of the pelliclecan be effectively utilized for various inspection, measurement andobservation. In this example, as described above, the pellicle is alsoattached on the surface of the mask substrate on which no photoresist isprovided.

[0163] According to the sixth embodiment, in addition to the effectacquired in the embodiments, the following effect can be acquired. (1) Aforeign matter is prevented from adhering to a mask by providing apellicle to the mask and the deterioration of a printed pattern causedby the adhesion of the foreign matter can be inhibited or prevented. (2)A resist for forming a light shielding pattern can be prevented frombeing peeled or being chipped when the pellicle is attached or detachedby bonding the pellicle sticking frame to the light shielding pattern orthe mask substrate in a state in which the pellicle sticking frame isdirectly touched. Therefore, a foreign matter can be prevented frombeing caused due to the peeling and a chip of the resist. (3) Thepattern written position accuracy of the electron beam writer can beenhanced by providing a mark pattern for correcting a position writtenby an electron beam from the electron beam writer on a mask itself.

[0164] Seventh Embodiment

[0165] Referring to FIG. 18 which is a plan showing a mask pattern, aseventh embodiment will be described below.

[0166] A reference number 1601 in FIG. 18 denotes a resist lightshielding surface, 1602 denotes an aperture of a phase 0 and 1603 and1604 denote an aperture of a phase π. The reference numbers 1602 and1603 denote a body pattern having a dimension in which pattern printingis enabled and 1604 denotes a so-called assist pattern the image ofwhich is directly not printed for enhancing the resolution performanceof a pattern in the vicinity. The minimum dimension of the body patterns1603 and 1604 is 0.2 μm (a dimension on a wafer, as the reductionpercentage of a lens is 4×, the dimension on a mask is 0.8 μm) or lessand though not shown, patterns of each dimension from 0.1 μm to 0.2 μmare provided on a wafer. The width of the assist pattern 1604 is 0.04 μmon a wafer (0.32 μm on a mask).

[0167] The mask is produced according to the first embodiment, however,it may be also produced according to the other embodiments except theproblem of selecting the material of the resist light shieldingmaterial. This mask is installed in an ArF excimer laser scanner thenumerical aperture NA of a lens of which is 0.6 and is printed on an ArFnegative resist.

[0168] As a result, the resist light shielding material 1601 showssufficient light shielding effect and no resist is left in the fieldregion. The body patterns 1602 and 1603 can be formed at the highdimension accuracy of 5% by Levenson phase shift. The resolution of thebody pattern between the assist patterns is higher than that in case aconventional type phase shift mask using Cr is used. The reason is thatas light shielding material is high resistance material or dielectricmaterial of a resist, guide wave effect (that is, waveguide effect) issmall and further, material hardly causing reflection is used. No 0/πdifference phenomenon also occurs in a Levenson phase shift part andhigh dimension accuracy is also acquired in that sense. However, thiseffect becomes remarkable when the width of a pattern is 0.16 μm or lessand pattern pitch is 0.32 μm or less in printing and the effect is thesame in a larger dimension as the case that the phase shift mask by theconventional method is used. According to the review of the resultacquired by varying the numerical aperture NA of a lens, when patternpitch is λ/NA or less, dimension accuracy is particularly high, comparedwith a conventional method.

[0169] Eighth Embodiment

[0170] A semiconductor integrated circuit is produced using the mask andthe pattern forming method according to the invention. (a) of FIG. 19 isa plan showing a representative pattern layout.

[0171] A reference number 1701 in (a) of FIG. 19 denotes a semiconductorregion such as an impurities diffused layer, 1702 denotes a contact withthe semiconductor region, 1703, 1704, 1706 and 1707 denote gate wiringand 1705 denotes a via hole of a wiring layer. To accelerate theoperational speed of a circuit and enhance packing density, it isrequired that the dimension of active gate wiring formed on thesemiconductor region such as the diffused layer is thin, the dimensionaccuracy is high and a gate wiring interval 1708 that determines pitchbetween gate wiring is narrow.

[0172] (b) of FIG. 19 is a plan showing a phase shift mask used forforming the gate wiring shown in (a) of FIG. 19. In this case, the maskproduced according to the first embodiment is used. However, the maskproduced according to other embodiments, for example, the mask formedaccording to the third embodiment can be also used. A reference number1709 shown in (b) of FIG. 19 denotes resist light shielding material anda shifter (a phase π) is alternately arranged in an aperture so thatLevenson arrangement is acquired. When a pattern is printed using thismask and an ArF scanner the numerical aperture NA of which is 0.6, thepattern interval 1708 of 0.1 μm extremely narrow is acquired, inaddition, the dimension in the phase π shown as 1704 and 1706 and thedimension in the phase 0 shown as 1703 and 1707 are coincident and aso-called pattern printing without 0/π difference can be realized.

[0173] Further, dimension difference between a location in which patternedges are relatively densely arranged such as 1703 and 1707 and alocation in which pattern edge are thinly arranged such as 1706 and 1707is small and is in a range of correction based upon the characteristicsof a lens. These owe to the reduction of waveguide effect and thereduction of reflection on the surface because light shielding materialis high resistance material and dielectric material.

[0174] It can be verified that in case a phase shift mask having Crlight shielding material is used, dimension accuracy is lower byapproximately 20%, compared with the case that the mask in thisembodiment is used. According to this gate pattern formation method, asemiconductor integrated circuit the operating frequency of which ishigh, the packing density of which is high and the chip of which issmall can be produced. As not only the number of chips acquired everywafer is increased but the manufacturing yield of the chip is enhancedwhen the chip becomes small, the manufacturing cost can be greatlyreduced.

[0175] Ninth Embodiment

[0176] A minute gate pattern is formed using a shifter edge phase maskin this embodiment. (a) of FIG. 20 shows the phase mask used at thattime, (b) of FIG. 20 shows a binary mask, and (c) of FIG. 20 shows aresist pattern formed by printing.

[0177] A reference number 1801 in FIG. 20 denotes the contour of apattern to be formed, 1802 denotes a resist light shielding pattern thewidth of which is narrow for forming gate thin wiring, 1803 denotesresist light shielding material, 1804 denotes an aperture for a phase 0,1805 denotes an aperture in which a shifter of a phase π is formed, 1806denotes transparent glass, 1807 denotes a light shielding pattern and1808 and 1809 denote a gate pattern formed by printing. For the maskshown in (b) of FIG. 20, a Cr binary mask in which the gate pattern 1808is made of Cr can be also used, however, in this case, a resist masklight shielding binary mask in which the gate pattern 1807 is made ofresist light shielding material is used.

[0178] After a first mask shown in (a) of FIG. 20 is installed inlithography equipment and a positive resist is exposed, a second maskshown in (b) of FIG. 20 is installed in the lithography equipment, theresist is exposed, normal heating processing and development are appliedto the resist and a resist pattern is formed.

[0179] In this embodiment, extremely thin gate wiring 1808 the width ofwhich is 60 nm can be acquired using an ArF scanner NA of which is 0.63reproducibly. In a normal shifter edge phase shift mask, as the problemof mechanical strength occurs in thin light shielding material 1802, theyield of a non-defective mask is low, however, in a mask in thisembodiment, such a problem does not occur and the yield of anon-defective mask is high.

[0180] Further, in blanks carved type shifter edge phase shift mask madeof Cr, as described above, when blanks of a shifter 1802 are carved,side etching is performed to prevent resolution performance from beingdeteriorated due to reflection on the side wall, however, as thin lightshielding material 1802 is thin, the quantity of side etching cannot besufficiently secured, it has an effect upon printing performance anddispersion in the dimension among printed resist patterns isapproximately 10%, while in this embodiment, dispersion in the dimensionamong printed resist patterns is 5% and can be reduced.

[0181] Tenth Embodiment

[0182] An electronic circuit composed of plural semiconductor memoryelements is produced on one semiconductor wafer using the mask and thepattern forming method according to the invention. (a) to (d) of FIG. 21are sectional views showing main processes for manufacturing the memoryelement.

[0183] As shown in (a) of FIG. 21, a P-type Si semiconductor 71 is usedfor a substrate and an element isolation region 72 made of SiO₂ isformed on it using element isolation technique. Next, a word line (agate electrode) 73 made of polycrystalline Si and having the thicknessof 150 nm for example is formed on the surface of the semiconductorwhere no element isolation region 72 is provided via a gate insulatingfilm made of SiO₂ and others and having the thickness of 200 nm or less,further, an SiO₂ film having the thickness of 150 nm for example isdeposited on it using chemical vapor deposition and a side spacer 74made of SiO₂ is formed on the side wall of the word line 73 byanisotropically processing. Next, an N-type diffused layer (a source ordrain region) 75 is formed by a normal method.

[0184] Next, as shown in (b) of FIG. 21, a data line 76 made ofpolycrystalline Si or high-melting point metal silicide or a laminatedfilm of these is formed via a normal process and the upside is coveredwith an insulating film made of SiO₂ and others. Next, as shown in (c)of FIG. 21, a capacitor electrode (a storage electrode) 78 made ofpolycrystalline Si, connected to the semiconductor region and extendedon the insulating film is formed via a normal process. Afterward, Ta₂O₅,Si₃N₄, SiO₂, BST, PZT, ferroelectric material or a composite film ofthese is deposited and an insulating film 79 for a capacitor is formed.Next, a conductor having low resistance such as polycrystalline Si,high-melting point metal, high-melting point metal silicide, Al and Cuis deposited and a plate electrode 80 is formed.

[0185] Next, as shown in (d) of FIG. 21, wiring 81 is formed via anormal process. Next, an electronic circuit composed of plural memoryelements is produced via a normal wiring forming process and apassivation process.

[0186] Only representative manufacturing processes are described above,however, normal manufacturing processes are used except the aboveprocesses. Even if the order of the processes is different, theinvention can be applied. The invention can be also applied to alithography process in the above element manufacturing process. Forexample, the invention is not necessarily required to be applied to aprocess in which a minute pattern is not required to be formed or aprocess in which high dimension accuracy is not required. The inventionis not applied to a through hole forming process in the passivationprocess and a pattern forming process for forming an ion implantationmask the pattern of which is large. Processes in which the patternforming process according to the invention is particularly effective arethe element isolation region forming process, the word line formingprocess, the capacitor electrode forming process and the wiring formingprocess.

[0187] Next, a pattern formed by lithography will be described. (a) ofFIG. 22 shows a pattern layout of a memory of a representative patternincluding memory elements. A reference number 82 denotes a word line, 83denotes a data line, 84 denotes an active region, 85 denotes a capacitorelectrode and 86 denotes the pattern of an electrode hole. (b) of FIG.22 shows a pattern layout of a memory of a representative patternincluding another memory elements. A reference number 87 denotes a wordline, 88 denotes a data line, 89 denotes an active region, 90 denotes astorage electrode and 91 denotes the pattern of an electrode hole. Theinvention is applied to the formation of a pattern of the word line andthe data line. In (b) of FIG. 22, the invention is also applied to theformation of a pattern of the storage electrode. The invention isapplied to a process using a minimum design rule except the aboveformation of patterns.

[0188] The characteristics of the element produced according to theinvention are satisfactory, compared with the characteristics of anelement produced using a conventional method. Concretely, theimprovement of the characteristics that as the dispersion in the widthof the word line is small, data reading speed is fast, thecharacteristics are stable and as the dispersion in the area of thestorage electrode is small, a data storage characteristic is stable canbe realized. Also, the yield of acquiring non-defective products of theproduced element is improved.

[0189] Eleventh Embodiment

[0190] Next, referring to FIG. 23 showing a section of the main partevery process, an example in which the invention is applied to themanufacture of an integrated circuit provided with a complementary MIS(CMIS) circuit according to a so-called twin well method will bedescribed.

[0191] As shown in (a) of FIG. 23, an N-type well 102 and a P-type well103 are formed on the upper surface of an N-type Si semiconductorsubstrate 101 that forms the principal part of a semiconductor wafer, afield insulating film 105 for isolating elements made of SiO₂ is formedusing selective oxidizing technique across both wells, and P-channelMISFET (Qp) and N-channel MISFET (Qn) are formed in a semiconductoractive region of each well surrounded by the insulating film 105.Reference numbers 111 and 112 are a P-type semiconductor region thatforms source and drain regions, 113 and 114 are an N-type semiconductorregion that forms source and drain regions, 106 and 107 are a gateinsulating film made of SiO₂ and others, and 115 and 116 are a gateelectrode provided on the gate insulating film. These gate electrodes115 and 116 are formed by reduction projection lithography equipmentusing a KrF excimer laser, photolithography using the photomask producedin the various embodiments of the invention and normal etching techniqueafter a low-resistance polysilicon film for example is deposited by CVD.The gate electrode is approximately 0.2 μm long. The semiconductorregions 111 to 114 are self-aligned with respective gate electrodes.

[0192] Next, as shown in (b) of FIG. 23B, after an interlayer insulatingfilm 118 made of SiO₂ is deposited by CVD and others, a polysilicon filmis deposited on it, is patterned by the reduction projection lithographyequipment using the KrF excimer laser, photolithography using thephotomask produced in the various embodiments of the invention andnormal etching technique, and wiring 119 and a resistor 120 are formedby partially doping impurities.

[0193] Next, as shown in (c) of FIG. 23, after an SOG film 122 made ofSiO₂ is deposited, plural connection holes 124 from which thesemiconductor regions and a part of wiring 199 are exposed are formedthrough the interlayer insulating film 118 and the SOG film 122 by thereduction projection lithography equipment using the KrF excimer laser,photolithography using the photomask produced in the various embodimentsof the invention and normal etching technique.

[0194] Next, as shown in (d) of FIG. 23, after a metallic film made ofaluminum (Al) or an Al alloy is deposited by sputtering, first layerwiring 126 and 127 are formed by patterning the metallic film by thereduction projection lithography equipment using the KrF excimer laser,photolithography using the photomask produced in the various embodimentsof the invention and normal etching technique.

[0195] Afterward, second layer wiring and third layer wiring (not shown)are formed on the first layer wiring by the similar method to theformation of the first layer wiring and a large-scale logic typesemiconductor integrated circuit (LSI) is manufactured.

[0196] When a circuit system of custom LSI is designed, mask debuggingis often performed particularly about the first layer wiring. To reduceTAT of such LSI, as the timing and the speed of supplying a maskcorresponding to the first layer wiring are extremely important and thenumber of required masks is many, it is extremely effective to apply theinvention to this process. The minimum pattern dimension of the secondlayer wiring is 0.35 μm and is thick enough, compared with thewavelength of 0.248 μm of exposure light, however, the photomaskaccording to the invention is also applied. The cost can be reduced,compared with a normal mask made of Cr and TAT can be reduced.

[0197] As understood from the above description, the invention can bealso applied to a semiconductor integrated circuit provided with amemory element such as a dynamic random access memory (DRAM), a staticrandom access memory (SRAM) or a flash memory (EEPROM), a semiconductorintegrated circuit provided with a logical circuit such as amicroprocessor or a hybrid semiconductor integrated circuit wherein thememory circuit and the logical circuit are provided on the samesemiconductor substrate. Particularly, for logic LSI provided with alogical circuit or system LSI wherein memory LSI and logic LSI areprovided, as a period from the design of a pattern to the manufacture isreduced according to the needs of a user and it is important to supplyto the user promptly, the invention for reducing mask production time isparticularly effective.

[0198] The technical concept of the invention is not limited to theapplication to a method of manufacturing a semiconductor integratedcircuit and for example, can be also applied to another electroniccircuit such as a liquid crystal substrate, a superconductive device, amagnetic head and a micro machine.

[0199] Twelfth Embodiment

[0200]FIG. 24 is a plan showing one mask used in a twelfth embodiment. Areference number 2101 in FIG. 24 denotes metallic light shieldingmaterial, 2102 denotes resist light shielding material and 2103 denotesan alignment mark for lithography equipment. For lithography equipment,a scanner is used and in the fourth embodiment, the phase shift mask isproduced. The same patterns to be printed are vertically arranged in ascanned direction of lithography equipment as shown as 2104 and 2105.However, the phases of the patterns are inverse. That is, a phase π, aphase 0 and the phase 0 are respectively arranged for body patterns2106, 2107 and 2108, however, the phase 0, the phase π and the phase πare respectively arranged for the corresponding patterns 2106′, 2107′and 2108′. The phase π is arranged for an assist pattern 2109, however,the phase 0 is arranged for a pattern 2109′. This mask is installed inthe scanner and is scanned and exposed. 2104 at that time is regarded asone chip and 2105 is carried so that it is overlapped with 2104, thatis, is exposed multiply. “0/π difference” between the dimensions ofprinted patterns is never made by exposing multiply. The method fulfilsthe effect particularly in a scanner. This reason is that in a scanner,exposure is performed using a part of a lens in the shape of a slit. Inthe meantime, in a method of exposing using the whole lens in a stepper,as the aberration of lenses is different between 2104 and 2105 and animage in which the aberration are added is printed, dimension accuracyis deteriorated.

[0201] The brief description of effect acquired by representatives ofthe inventions disclosed in the application is as follows. (1) As thenumber of the manufacturing processes of the phase shift mask is reducedand processes in which a foreign matter often occurs such as theformation of a Cr film by sputtering and the etching of the Cr film arenever used when a mask pattern for forming a minute pattern is produced,the mask manufacturing yield is also enhanced. The reduction of thenumber of manufacturing processes is also greatly effective in TAT forproducing a mask. (2) The control accuracy of a phase angle is enhanced.Particularly, in the method of forming the shifter on the blansk in thefirst to third embodiments, this effect is large. As there is hardlymicro loading effect by etching, a phase angle can be unified in variousdimensions and the dimension controllability of a printed pattern ishigh. (3) As a part where a phase angle varies, that is, the edge of theshifter is covered with a light shielding film (for example, aphotoresist) made of dielectric material, high resistance material ororganic material, reflection from the side wall of the light shieldingfilm and guide wave effect can be reduced in printing, a problem of theshortage of mask pattern strength by miniaturization does not occur andthe miniaturization of a printing pattern is facilitated. Superficialreflection is also small and the dimension accuracy of a printed patternis high. 0/π difference between the dimensions of Levenson type phaseshift masks is small. (4) As a metal light shielding region is providedin the periphery of the mask substrate of the photomask and the markpattern for detecting the information of the photomask is formed byremoving a part, the information detection capacity of the photomask canbe enhanced. No foreign matter is caused when the mask is installed inlithography equipment. (5) The mask can be easily identified byproviding a mask identification mark on the metal plate. (6) By theeffect described in the above (1) to (5), the performance, thereliability, TAT for development and the manufacturing yield of theelectronic circuit such as a semiconductor integrated circuitmanufactured using the photomask according to the invention can beenhanced.

What is claimed is:
 1. The manufacturing method of an electron device, wherein: a photosensitive film provided to the surface of a workpiece to be an electron device is exposed via a mask wherein a phase shifter is partially formed on, the flat surface of a transparent plate and a light shielding film made of non-metal is partially provided with the film covering the end of the phase shifter and is developed.
 2. The manufacturing method of an electron device according to claim 1, wherein: the section in the direction of the thickness of the end of the phase shifter is tapered.
 3. The manufacturing method of an electron device according to claim 1, wherein: the light shielding film is made of dielectric material, high resistance material or organic material.
 4. The manufacturing method of an electron device according to claim 1, wherein: the light shielding film is a photoresist mainly made of novolac resin, phenol resin or polyaniline resin.
 5. The manufacturing method of an electron device, wherein: a photosensitive film provided to the surface of a workpiece to be an electron device is exposed via a mask wherein a light shielding film made of non-metal is partially provided on the surface of a transparent plate on which a concavity or a convexity is partially formed with the film covering the end of the concavity or the convexity and is developed.
 6. The manufacturing method of an electron device according to claim 5, wherein: the light shielding film is made of dielectric material, high resistance material or organic material.
 7. The manufacturing method of an electron device according to claim 5, wherein: the light shielding film is a photoresist mainly made of novolac resin, phenol resin or polyaniline resin.
 8. A pattern forming method, wherein: a light shielding film pattern is projection-exposed on a photosensitive film provided on the surface of a workpiece using a mask wherein phase shift means that inverts the phase of exposure light in printing is partially formed on the surface of a transparent plate and the light shielding film pattern made of non-metal is partially provided with the pattern covering the end of the phase shift means and the exposed photosensitive film is developed.
 9. A pattern forming method according to claim 8, wherein: the transparent plate is composed of a transparent substrate and a first transparent film provided on the surface; the phase shift means is composed of a second transparent film formed on the surface of the first transparent film; and the refractive index of the exposure light in the first transparent film is larger than that of the transparent substrate and is smaller than that of the second transparent film.
 10. A pattern forming method according to claim 8, wherein: the phase shift means has a concavity or a convexity formed on the surface of the transparent plate.
 11. A pattern forming method according to claim 8, wherein: the light shielding film is made of dielectric material, high resistance material or organic material.
 12. A pattern forming method according to claim 8, wherein: the light shielding film is a photoresist mainly made of novolac resin, phenol resin or polyaniline resin.
 13. A photomask composed of transparent mask material and light shielding material for shielding exposure light, wherein: the light shielding material is made of photosensitive composition; the mask material includes a region in which a metallic film is formed; and a character or a mark for identifying the mask is formed in the region by the photosensitive composition.
 14. A pattern forming method, wherein: one photosensitive film provided on the surface of a workpiece is projection-exposed multiply using a first mask wherein phase shift means that inverts the phase of exposure light in printing is partially formed on the surface of a transparent plate and a light shielding layout pattern made of non-metal is provided with the pattern covering the end of the phase shift means and a second mask provided with the same second light shielding layout pattern as the light shielding layout pattern of the first mask and second phase shift means the phase of which is inverse to that of the phase shift means of the first mask and the exposed photosensitive film is developed.
 15. The manufacturing method of an electron device, wherein: when the light shielding pattern is printed on the surface of a workpiece to be an electron device using a mask on the surface of which a light shielding pattern made of a photoresist is arranged by projection lithography equipment, the surface of the photoresist is printed without touching the surface to the stage of the projection lithography equipment and its carriage means. 